dcrahn is correct...
I would just like to add the problem with a MLS style gasket is there is generally no give so if you are not right on the tune and something goes wrong you normally do more damage, melt the head, pistons, damage valve train, etc... I reccomend MLS gaskets only to customers that have a good understanding with tuning, and the consequences.
The Fel-Pro MLS gasket come in a little cheaper $60/each and I find they have a little more give over the Cometic. The block and head surface have to be correct to use a MLS gasket.
Based on your sig I would use a Fel-Pro 10111